Tissue marking generally is a method of marking a position in a body, such as a specific position on tissue or an organ, to allow re-visiting of the position at a later time to check for progress or developments of an ailment or a treatment, or to allow re-treatment at the same site. As an example, tissue marking can be used during biopsy or other tissue-removal procedures to accurately mark the site of the tissue-removal or biopsy, to allow a treatment-giver to later return to the same site if desired, e.g., to monitor the status of the tissue in question, or to do another biopsy.
Such tissue marking can be useful in procedures relating to colon or rectum biopsies or tissue removal, prostrate biopsies, or breast biopsies.
Specifically with respect to breast biopsies, it is not uncommon in modern breast biopsies, e.g., using a mammotone breast biopsy system sold under the trademark name BIOPSYS, from Ethicon Endo-Surgery, Inc., for all evidence of a lesion to be removed during biopsy. Removing all trace of the tissue also removes identifying features from the site, and makes it difficult to return to the same location later, to re-check the site. This dilemma, created by a removal of a potentially malignant breast mass or cluster of microcalcifications during core biopsy, can be ameliorated by placing radiographically visible markers immediately after the biopsy. The marker, e.g., a radiopaque material, can be used to help locate the biopsy site in case malignancy is determined, thereby enabling return to the same site and optionally a subsequent treatment such as surgical excision, even if the mammographic findings associated with the original lesions were removed completely.
One localization method involves placing a metallic clip (e.g., sold under the trade name Micromark(trademark), from Biopsys Medical) through an 11- or 14-gauge probe of a motorized, vacuum core-cutting biopsy device, and attaching the clip to the site of a biopsy, to mark the location of the biopsy. Such clips measure approximately 3 mm across, and are permanent and radiopaque. The use of marking clips has been described in the following articles: Burbank, Fred, MD, Farcier, Nancy, MD, xe2x80x9cTissue Marking Clip for Stereotactic Breast Biopsy: Initial Placement Accuracy, Long-term Stability, and Usefulness as a Guide for Wire Localization,xe2x80x9d Radiology 1997; 205:407-415; Liberman, Laura, MD, Dershaw, David, MD, Morris, Elizabeth A., MD, Abramson, Andrea F., MD, Thorton, Cynthia M., R T (R)(M), Rosen Paul Peter, MD, xe2x80x9cClip Placement After Stereotactic Vacuum-Assisted Breast Biopsy,xe2x80x9d Radiology, 1997; 205:417-422.
Another example of an application for tissue marking is in prostate biopsies. It is recognized that initial biopsies may not be fully determinative in the prostate. See, e.g., Jonathan I., MD, xe2x80x9cAre You Getting Maximum Diagnostic and Prognostic Information from your Prostate Needle Biopsy?xe2x80x9d Contemporary Urology, 106, April 1999. Tissue marking can ensure that the tissue of non-determinative initial biopsies can be monitored for progressive disease, and that if necessary a follow-up biopsy can be performed at the site of the initial biopsy.
Other methods of tissue marking or xe2x80x9clocalizationxe2x80x9d are described in articles of the technical literature: see e.g., Fajardo, Laurie L., MD, Bird, Richard E., MD, Herman, Cheryl R., MD, DeAngalis, Gia A., MD, xe2x80x9cPlacement of Endovascular Embolization Microcoils to Localize the Site of Breast Lesions Removal at Sterotactic Core Biopsy,xe2x80x9d Radiology, 1998, 206: 275-278. Still another method of localizing breast lesions is described at Goldberg, Ronald P., MD, Hall, Ferris M., M.D., and Simon, Morris, MD. xe2x80x9cPreoperative Localization of Non-Palpable Breast Lesions Using a Wire Marker and Perforated Mammographic Grid,xe2x80x9d Radiology 146: 833-835, March 1983; see also U.S. Pat. Nos. 4,341,220 and 5,665,092.
The invention provides a method of tissue marking. The method includes the use of detectable, preferably radiopaque particles delivered to a tissue site for later detection. The particles can preferably be delivered into the body to a desired site by injection using a hypodermic needle and syringe, or another similar instrument, or percutaneously, with the assistance of a biopsy probe. Microparticles can preferably be of an average size in the range from about 100 to 1000 microns, more preferably from about 200 to 500 microns, and most preferably from about 251 to about 300 microns, in transverse, cross-sectional dimension. The microparticles can preferably be permanently radiopaque, and may optionally comprise a carbon coating.
An optional carbon surface may include, for example, pyrolytic carbon, e.g., isotropic carbon such as low temperature isotropic carbon, vitreous carbon, or any other useful form of carbon. The carbon can be coated onto a particle substrate as a thin coating or film, thereby creating a particle having a highly biocompatible carbon surface. While not required, pyrolytic carbon can be preferred.
The particle substrate can be but is not necessarily biocompatible, and should be capable of withstanding the conditions of the process for coating a carbon surface onto the substrate, which might include elevated temperatures. In particularly preferred embodiments, particle substrates can be radiopaque, most preferably permanently radiopaque. Exemplary radiopaque materials can include metals and metal oxides such as zirconium oxide and aluminum oxide, gold, titanium, silver, stainless steel, oxides and alloys thereof, etc.
The microparticles can be delivered using a fluid carrier, which can be any biologically compatible material capable of delivering the microparticles to a desired tissue site, such as a biologically compatible suspension, solution, or other form of a fluid or gel. Examples of materials useful in biologically compatible carriers include saline, dextrans, glycerol, polyethylene glycol, corn oil or safflower, other polysaccharides or biocompatible polymers, methyl cellulose, glucan, agarose, etc., either singly or in combination.
The use of microparticles in tissue marking methods, preferably by injecting through a hypodermic needle and syringe or a like instrument, has advantages over other tissue marking methods. For instance, delivery of microparticles using a needle and syringe allows very precise delivery of microparticle markers to a desired tissue site, this is particularly true if a biopsy probe used to perform a biopsy is used to assist delivery of microparticles for tissue marking, without first moving the biopsy sheath. Additionally, microparticles can be used in tissue locations where other types of tissue markers are not or cannot be used. For example, some tissue locations such as the colon or rectum do not lend themselves to the use of marking clips, yet it is possible to deliver microparticles to these locations for effective marking. And, embodiments of useful microparticles having a carbon-coated surface are very biocompatible. As another advantage, preferred embodiments of the microparticles can be permanently radiopaque, e.g., by virtue of a permanently radiopaque particle substrate. The location of permanently radiopaque particles can be monitored, by known methods, for as long as the radiopaque microparticles remain in a body.
An aspect of the invention relates to a method for tissue marking. The method includes delivering detectable microparticles to a tissue site and detecting the microparticles.
Another aspect of the invention relates to a method of tissue marking. The method includes injecting detectable microparticles to a tissue site through a hypodermic needle, and detecting the microparticles.
Yet another aspect of the invention relates to a method for marking a biopsy. The method includes performing a biopsy and marking the site of the biopsy using detectable microparticles injected through a hypodermic needle.
Yet another aspect of the invention relates to a method for marking a site of tissue removal. The method includes performing a tissue removal procedure and marking the site of the tissue removal using detectable microparticles injected through a hypodermic needle.
For purposes of the present disclosure, the following terms shall be given the following meanings.
The term xe2x80x9cbiocompatible,xe2x80x9d refers to materials which, in the amount employed, are non-toxic and substantially non-immunogenic when used internally in a patient, and which are substantially insoluble in blood. Suitable biocompatible materials include ceramics, metals and metal oxides such as titanium, gold, silver, stainless steel, oxides thereof, aluminum oxide, zirconium oxide, etc., carbon such as pyrolytic carbon or low temperature or ultra low temperature isotropic carbon.
The term xe2x80x9cdetectablexe2x80x9d refers to materials capable of being detected during or after injection into a mammalian subject, by methods generally used for monitoring and detecting such materials, e.g. magnetic resonance, X-ray, ultrasound, magnetotomography, electrical impedance imaging, light imaging (e.g. confocal microscopy and fluorescence imaging) and nuclear imaging (e.g. scintigraphy, SPECT and PET). Examples include contrast-enhancing agents such as radiopaque materials. Contrast-enhancing agents may be either water soluble or water insoluble. Examples of water soluble radiopaque materials include metrizamide, iopamidol, iothalamate sodium, iodomide sodium, and meglumine. Examples of water insoluble radiopaque materials include metals and metal oxides such as gold, titanium, silver, stainless steel, oxides thereof, aluminum oxide, zirconium oxide, etc.